Genetic Diversity Analysis Of Rice Recurrent Selection Population With ABCG15

Recurrent selection is one of the main methods of moden crop improvement.It is widely used in com and other cross-pollination crops,and has achieved remarkable results.For self-pollinating crops,such as rice,because of its characteristic of self-pollination,recurrent selection is not applicable.However,the discovery of Male Sterility makes this method possible for those self-pollinating crops like rice.This study takes 35 maintainer lines of rice as base materials and Sichuan recessive sterile materials H2S of which the sterile gene is named ABCG15 as genetic tools.Use the codominant marker SSR 147,select BC1F1 with heterozygousABCG15 and mix equal amounts of seeds to build base groups.The combination of molecular maker and agronomic traits leads to comprehensive evaluation.The results of the experimental study are presented as follows:1.35 maintainer lines of parent materials and H2Sw(Sichuan recessive male sterile wild type)of main agronomic characters of variance analysis shows that the differences between the traits reaches a significant or very significant level,indicating that there are significant genetic differences in experimental combinations of eight agronomic traits as yield,1000-grain weight,number of effective panicle,plant height,spikelet number,seed setting rate,grain length and the ratio of length to width.Maximum yield value is 464.89(Kangfeng B),minimum value is 210.67(Jing23B),average value is 322.94;Maximum grain weight value is 30.48(Yixiang 1B),minimum value is 18.14(Dxiang B),average value is 24.11;Maximum grain length to width value is 4.63(Dxiang B),minimum vale is 2.44(HuaB),average value is 3.31.2.Among 50 sites of the experiment,there are 7 highly polymorphic loci,32 moderate polymorphic loci and 11 low polymorphic loci.The average Shannon index H is 0.5914 ± 0.2182.The average observed heterozygosity Ho is 0.1222 ±0.2934.The mean expected heterozygosity He is 0.3945 ± 0.1518.It shows that the heterogeneity of those 35 maintainer lines of rice is not high and the overall genetic diversity is in intermediate level.3.For the base materials and the improved groups C1?C2?C3?C4,their polymorphic loci are 50,47,43,46,47 respectively and the proportion of polymorphic loci are 100%,94%,86%,92%,94%.It shows that with the increase of improvement rounds,polymorphic loci and its proportion increase but with fluctuations.In the first and fourth round,polymorphic loci and its proportion are same.4.For parent base materials and improved groups C1?C2?C3?C4,their average expected heterozygosity are 0.3889,0.3613,0.3092,0.3346,0.3471.It shows that with the increase of improvement rounds,the average expected heterozygosity decreases with fluctuations.5.For parent base material and its improvement groups C1?C2?C3?C4,the average distances are 0.5224,0.4911,0.4681,0.4280,0.4244.The significance test results shows that except C1 which obtains no significant difference from the parents,the rest three generations obtains very significant difference.The average genetic distances decrease with the increase of improvement rounds.6.For parent base materials and its improved groups C1?C2?C3?C4,the genetic diversity index are 0.5914,0.5397,0.4663,0.5059,0.5126 respectively.It shows that the genetic diversity indexes of improved groups C1?C2?C3?C4 are lower than that of base group.7.Combining ability variance analysis shows that the differences between the combinations of traits reaches a significant or very significant level,indicating that there are significant genetic differences in experimental combinations of six agronomic traits as yield,1000-grain weight,number of effective panicle,plant height,spikelet number and seed setting rate.For paternal general combining ability,except spikelet number,the variance of the rest traits reaches a significant or very significant level,indicating that the majority of these agronomic traits are controlled by a both of additive and non-additive effect.The results of the system clustering of six agronomic traits GCA is consistent with the molecular level Cluster analysis.8.General combining ability is an important genetic parameters for hybrid rice.In four cycles of generations,six of agronomic traits have either positive or negative GCA relative effect values.Maximum weight GCA positive value is 0.5304(C4F1),higher than 0.0853(C1F1).Maximum yield GCA positive value is 1.0734(C3F1),higher than 0.0840(C1F1).Maximum plant height GCA positive value is 0.2603(C3F1),higher than 0.1567(C4F1).Maximum effective panicle GCA positive value is 0.3661(C1F1),higher than 1.4028(C4F1).Maximum Spikelet number GCA positive value is 0.5818(C4F1),higher than 0.4310(C3F1).Maximum seed setting rate GCA positive value is 1.0421(C2F1)and the minimum is-2.0548(C4F1).The average GCA of every round fluctuates.